富CO2流体混合物在多组分电解质水溶液中的溶解度和体积性质的计算模拟及应用

近年来，CO2捕获与储存（CCS）被认为是一种有效的减少大气中CO2排放量的方法，深部咸水层因封存储量大被视为CO2封存地点的最佳选择之一。工业排放的CO2气体中通常含有N2、O2、Ar、CH4、H2S等成分，将它们一起封存在深部咸水层则可以减少成本，但是定量评估必须要了解这些富CO2流体混合物的体积与相平衡性质、它们在深部咸水层中的溶解度以及咸水层的体积变化。过去CCS研究一直把它们近似为CO2-H2O-NaCl体系，本项目欲从实际出发，首先建立一个通用的CO2-N2-O2-Ar-CH4-H2S体系的流体状态方程，用来预测其气-液相平衡和体积性质，然后结合Pitzer活度系数理论模拟中低温压下这些混合气体在多组分电解质溶液（Na+、Ca2+、K+、Mg2+、Cl-、SO42-）中的溶解度，最后结合气-水-盐密度模型来预测这些混合气体溶解后咸水层的体积变化，为相关动力学研究提供理论参数。

CO2 capture and sequestration (CCS) has been regarded as one valid approach to reduce the amount of CO2 emissions to the atmosphere in recent years, and deep saline aquifers are one of the best options due to high potential capacity of CO2 storage for their wide distribution. N2, O2, Ar, CH4 and H2S have always been found with CO2 (the major greenhouse gas) in flue gases generated from industrial processes, and the co- sequestration of both them into deep saline aquifers will reduce the costs of CCS. However, quantitative estimation requires the knowledge of volumetric and phase equilibrium properties of CO2-rich fluid mixture, gas solubility in deep saline aquifers and the volumetric changes after the dissolution of gases. In previous CCS studies, they are approximated as the CO2-H2O-NaCl system. This work will consider the fact, and firstly a general equation of state of CO2-N2-O2-Ar-CH4-H2S fluid mixtures has been developed to predict the vapor-liquid equilibrium and PVTx properties. Then, a model of gas solubility in multi-component electrolyte solution (including Na+, Ca2+, K+, Mg2+, Cl- and SO42-) is presented by combining the Pitzer activity coefficient theory with this new equation of state. Finally, the solubility model and the gas-water-salty density model are combined to predict the volumetric changes after the dissolution of mixture gases in deep saline aquifers, which will provide theoretical parameters for corresponding dynamic research.